1. Field of the invention:
The present invention relates to an alarm system for crime prevention installed mainly for domestic use.
2. Prior art:
Various alarm systems have been proposed which guard against unauthorized entry by means of a pair of magnet switches mounted on movable openings such as doors, windows or the like. Infrared alarm systems are also known in which a moving object is detected by infrared ray sensors installed outdoors, indoors, etc.
The foregoing devices have disadvantages. With the alarm system with the magnet switches, it is necessary to switch it on and off and switching it on again is sometimes forgotten. Moreover, it is often the case that the alarm system is misoperated by children, etc. Also it sometimes happens that a family member goes in and out without switching off the alarm system. Thus, the fact is that the alarm system of this type is not favorably used due to its troublesome operation.
With the infrared ray sensor alarm system, since this alarm system detects pets and family members, it is necessary to disengage the system before entering the house and to switch it on when going out. Since this alarm system operates at night, it cannot distinguish between family members moving about at night and intruders. Thus, the fact is that this alarm system is useful only when nobody is in the house.
Further, with the infrared alarm system, whether it is installed outdoors or indoors, it also senses pets, objects, and with no capability of distinction between family members and intruder. Thus, it is often the case that a main switch is left off and as a result the system does not operate in time of need.